[mkgmap-dev] gui for areas.list ?

Wed Aug 26 17:24:51 BST 2009

Hi

> L>  the tiles rendered with Mkgmap. The red tiles in Denmark are caused
> L>  by all the house numbers which cause the guesstimate mechanism
> L>  (--max-nodes) of splitter to be fooled in thinking that Mkgmap could
> L>  produce working maps for those areas. Splitter should be more
> L>  intelligent about determining the max size of an area, ultimately.
>
> Ahh yes, that rings a bell now that you mention it. I'm open to suggestions
> on how this could be improved, unfortunately I don't have enough experience
> with the limits yet to know what might be the best approach. At this stage

Denmark is a separate problem, one that wasn't aware of until the
other day after Morten's message.  The large number of tags on
nodes is causing an out of memory in mkgmap, but wouldn't actually
cause any problems in the map (as the nodes are not included in the
map currently).

There are two things that typically overflow RGN and NET.

RGN depends on the number of points and ways.
NET depends on the number of roads and how how many levels they appear
on (ie a motorway will use more space than an alley)

The amount of space taken up has a lot of 'it depends' in it, but my
size estimation in MapArea in mkgmap uses the following formulas:
   A point takes up at most 9 bytes
   A line takes up 11 plus 2*(number of points) bytes.

These are just estimates, the bytes taken by a way depends on how
widely the points are spaced and if it wiggles back and forth or
tends in the same direction.

Of course nodes that don't end up in the map take zero, but may be a
significant part of the input particularly in well mapped areas where
people have run out of important things to map and started to map
litter bins or whatever.

So counting the number of nodes is only a good estimate if the
relative proportions of unused nodes, POIs, ways and roads is on
average similar across all areas.

This may be a reasonable assumption in areas mapped by hand though it
is likely to change as more things get mapped, but is likely to be
completely wrong in areas where there have been bulk imports.

..Steve